October 14, 2011
This week, dinosaur fans got a sneak preview of one of the most beautiful theropod dinosaur skeletons yet discovered. Depending on what the critter turns out to be, the specimen may alter our understanding of how widespread partial coats of fuzzy feathers were among dinosaurs.
Originally reported in the German newspaper Der Spiegel and later mentioned by the Nature news blog, the new specimen is a nearly complete juvenile theropod dinosaur. Even better, traces of skin and possible feathers can be seen on the fossil. Contrary to those reports, though, the specimen is geologically older than the 135 million years attributed to it in the press. The geological and preservational qualities of the fossil look identical to those from the famous Jurassic limestones that have yielded so many other exceptional fossils. I contacted Oliver Rauhut, paleontologist and conservator of Bavaria’s state paleontological and geological collections and one of the researchers currently studying the specimen, and asked about the animal’s geologic context. He replied: “The theropod is indeed from the Jurassic, from the unit underlying the Solnhofen Formation, and thus 145 to 150 million years old rather than the 135 given in the press release.”
That is nearly all that has been publicly released, but the specimen was also featured in a talk titled “New Information on Late Jurassic Theropod Dinosaurs from Southern Germany” given by Rauhut and paleontologist Christian Foth at the recent Latin American Conference of Vertebrate Paleontology in San Juan, Argentina. Scuttlebutt from that conference has already started fueling speculation about how important this new dinosaur might be. Of course, we will have to wait for all the published results to find out the essential details, but the presence of simple feather traces on this specimen could have important consequences for our understanding of dinosaurs.
So far, all the theropod dinosaurs definitively known to have possessed feathers belonged to a subgroup called coelurosaurs. (The question of whether the non-coelurosaurian theropod Concavenator had feather-like bristles on its arms remains unresolved.) That includes another, roughly 151-million-year-old theropod from Germany with preserved feather traces called Juravenator. If the new specimen turns out to be a coelurosaur, then we will gain a little more resolution about how common feathers were among this group and possibly details of the development of those feathers as coelurosaurs matured. But what if it turns out to be something else? If the new dinosaur is something other than a coelurosaur, then the fact that it was at least partially covered in simple feathers would indicate that either: 1) such structures evolved multiple times among dinosaurs, or 2) the forerunners of feathers were inherited from an even older common ancestor. In either case, simple feathers or feather-like structures may have been more widespread among theropods than previously understood.
In fact, we already know that dinosaurs other than coelurosaurian theropods had feather-like structures on their bodies. The ornithischian dinosaurs Tianyulong and Psittacosaurus—two genera very, very, very distant from the theropod dinosaurs—were partially covered by bristles that were structurally similar to feathers. The presence of these coverings on dinosaurs so distantly related to coelurosaurs has already raised the possibility that other dinosaurs shared this feature. What we lack are the exceptionally preserved fossils to test the ideas about how widely feather-like body coverings evolved and how widely they were shared. Perhaps the new dinosaur and the work by Rauhut and Foth will help paleontologists broaden their understanding of what dinosaurs looked like and how feathers evolved. Regardless of what subgroup the animal is eventually assigned to, the unnamed dinosaur is a wonderful specimen. I cannot wait to find out more.
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